[Grml] Boot USB sans IDE noise

One user noticed that older IDE drives (CD, HDD) make noise, depending on age, case vibrations. His USB drive is very quiet. He boots grml from that.

Can he boot from USB without powering IDE drives? Grml has an orderly IDE power-off procedure at shutdown. You hear the IDE hard drives click off one by one. The question is best method to invoke the commands at boot time.

Of course he can always unplug the power cables manually :-) But customers don't like that. :-) Software control is better anyway.